Which vehicles are prohibited from using a road sign-posted like this?

This traffic sign means that trucks with a permissible total mass exceeding 3.5 tons, as well as truck tractors, are not allowed to use the road. The sign specifically targets large and heavy vehicles to prevent them from entering, usually for reasons such as road safety, noise reduction, or protection of the road surface. Cars with trailers are not included unless the sign explicitly states otherwise. You selected both correct answers, which shows you recognized the rule correctly. Remember: this sign always refers to heavy trucks and truck tractors, not to cars with trailers.